Several image changing mechanisms exist in the advertising and promotional display field. These devices in the most basic sense will first display one image and then replace it with another (secondary) image as the device is activated by the user.
Many of the aforementioned class of image changing mechanisms are restricted to the maximum size of the image area due to the size requirements of the necessary (hidden) components of the mechanism. In addition to this, many like mechanisms reveal the secondary image(s) in a predictable manner.